Spatial distribution and risk assessment of metals in overlapped areas of farmland and coal resources soils, Xuzhou, China

摘要

In this case study, we studied pollution in overlapped areas of farmland and coal resources in the north of Xuzhou, Jiangsu Province, China. Totally 107 soil samples taken from the grid distributed locations were assayed for the trace elements, Cu, Cd, Pb, Zn, Cr, Hg and As. The spatial distribution of the pollutant concentrations was evaluated with respect to the locations of the potential contamination sources. The contamination level of this region was assessed based on the Soil Pollution Control Regulation of China. Results indicated that the contents of Cd, Hg, Cu, Pb, Zn, and Cr, especially the former two, are higher in the soil than the background. The ArcGIS data showed that pollutants are more likely to be detected in the vicinity of the contamination sources. Pb, Zn, Cu, and Cr are mainly spotted in the southwest and east of the region, particularly fly ash yards and new industry areas. Cd and As are more spotted in the straight north of the region, and Hg in the east and west. The results from the single factor pollution index showed that Cd pollutes 43.9% of sample locations heavily and 28.0% moderately, whereas the contents of the other six trace elements are safely below the detectable level of pollution. According to the pollution load index, twenty-six sample locations are heavily polluted. The potential ecological risk from the seven trace elements, in the order of decline, is Hg, Cd, Cu, As, Pb, Cr, and Zn. Five sample locations are of the severe ecological risk.